1. Technical Field
The present invention relates generally to a low-power encryption apparatus and method and, more particularly, to a low-power encryption apparatus and method that can convert the intermediate operation values of a low power encryption algorithm into random numbers, thereby providing an encryption algorithm that is secure from differential power analysis attacks.
2. Description of the Related Art
Block ciphers are core components that are most widely used in encryption applications that enhance the security of communication and stored data in a variety of types of devices, and function to provide confidentiality by encrypting data on a specific length (64-bit, or 128-bit) basis. Furthermore, block ciphers are used for a hash function, a message authentication code, a random number generator, etc. In accordance with these uses, block ciphers should be designed to be suitable for the characteristics of devices and encryption applications, and are implemented as software that is run by chips specific to the devices or the central processing units (CPUs) of the devices.
Meanwhile, as an attack against block ciphers, an attack method called a side-channel analysis attack was introduced by Paul Kocher in 1996. A side-channel analysis attack attacks a cipher using physical information that is generated in a low-power encryption apparatus in which the encryption algorithm has been implemented, unlike a conventional cipher analysis attack that is based on a mathematical theory. The physical information that is used in such side-channel analysis attacks includes the operation time, power consumption level or radiated electromagnetic waves of algorithms. Such side-channel analysis attacks are serious threats against low-power encryption apparatuses in which actual encryption algorithms have been implemented.
In particular, power analysis attacks, which are a type of side-channel analysis attacks, discover a private key by analyzing the characteristics of power consumption measured in a low-power encryption apparatus at the time at which data related to the key is processed while an encryption algorithm is operating. Power analysis attacks may be classified into simple power analysis attacks and differential power analysis attacks.
Meanwhile, with regard to a Lightweight Low-power Encryption Algorithm (LEA) developed for the purpose of software cryptographic operations in a low-power environment, although a block cipher technique was disclosed in the paper entitled “HIGHT A New Block Cipher Suitable for Low-Resource Device” at the Workshop on Cryptographic Hardware and Embedded Systems held in 2006, the block cipher technique disclosed in the paper is susceptible to the above-described side-channel analysis attacks and thus exhibits weakness in security.